Electronic graphics produced via electrographic processes, inkjet processes, and the like, is rapidly becoming a preferred method for the formation of images. The Scotchprint.TM. Electronic Graphics Systems commercially available from Minn. Mining and Manufacturing Company of St. Paul, Minn. ("3M Company") uses an electrostatic process for forming an image and transferring that image to a durable substrate. One description of the process is found in U.S. Pat. No. 5,114,520 (Wang et al.).
The image formed on a durable substrate requires protection from abrasion and ultraviolet light. An optically clear, transparent overlaminate, comprising an optically clear, transparent durable film covered on a major surface by an optically clear, transparent pressure sensitive adhesive, is preferably applied over the image on the durable substrate. Commercially available clear, transparent overlaminates include Product Nos. 8910, 8911, 8912, 8913, 8920, 8930, and 8931 films from the Commercial Graphics Division of 3M Company, St. Paul, Minn. Of these, 8913 and 8930 are optically clear. Some of the clear, transparent overlaminates include a vinyl or polyester film covered with a pressure sensitive adhesive, which is in turn is protected by a paper or polyester liner until usage. Other clear, transparent overlaminates include a vinyl or polyester film covered with a hot melt adhesive, and a scrim liner to prevent blocking.
In the absence of the use of a clear, transparent overlaminate, some fabricators apply a protective clear coat of a vinyl/acrylic material, such as Product Nos. 3920, 8920, 9720, 6620I, and 2120 protective coatings from the Commercial Graphics Division of 3M Company to protect the durable, imaged substrate. But such application of a liquid to a solid flat surface is subject to the inconsistencies of climate, circumstances, and craftsmen.
While the optically clear, transparent overlaminates known in the art are quite acceptable for large format graphics uses, vinyl-based optically clear, transparent overlaminate films remain extremely elusive to achieve.